/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __DFS_BUF_H__
#define __DFS_BUF_H__

#include <linux/list.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/uio.h>

/*
 *	Base types
 */

#define DFS_BUF_DADDR_NULL	((dfs_daddr_t) (-1LL))

typedef enum {
	XBRW_READ = 1,			/* transfer into target memory */
	XBRW_WRITE = 2,			/* transfer from target memory */
	XBRW_ZERO = 3,			/* Zero target memory */
} dfs_buf_rw_t;

#define XBF_READ	 (1 << 0) /* buffer intended for reading from device */
#define XBF_WRITE	 (1 << 1) /* buffer intended for writing to device */
#define XBF_READ_AHEAD	 (1 << 2) /* asynchronous read-ahead */
#define XBF_ASYNC	 (1 << 4) /* initiator will not wait for completion */
#define XBF_DONE	 (1 << 5) /* all pages in the buffer uptodate */
#define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
#define XBF_WRITE_FAIL	 (1 << 24)/* async writes have failed on this buffer */

/* I/O hints for the BIO layer */
#define XBF_SYNCIO	 (1 << 10)/* treat this buffer as synchronous I/O */
#define XBF_FUA		 (1 << 11)/* force cache write through mode */
#define XBF_FLUSH	 (1 << 12)/* flush the disk cache before a write */

/* flags used only as arguments to access routines */
#define XBF_TRYLOCK	 (1 << 16)/* lock requested, but do not wait */
#define XBF_UNMAPPED	 (1 << 17)/* do not map the buffer */

/* flags used only internally */
#define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
#define _XBF_KMEM	 (1 << 21)/* backed by heap memory */
#define _XBF_DELWRI_Q	 (1 << 22)/* buffer on a delwri queue */
#define _XBF_COMPOUND	 (1 << 23)/* compound buffer */
#define _XBF_LRU_DISPOSE (1 << 24)/* buffer being discarded */

typedef unsigned int dfs_buf_flags_t;

#define DFS_BUF_FLAGS \
	{ XBF_READ,		"READ" }, \
	{ XBF_WRITE,		"WRITE" }, \
	{ XBF_READ_AHEAD,	"READ_AHEAD" }, \
	{ XBF_ASYNC,		"ASYNC" }, \
	{ XBF_DONE,		"DONE" }, \
	{ XBF_STALE,		"STALE" }, \
	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
	{ XBF_SYNCIO,		"SYNCIO" }, \
	{ XBF_FUA,		"FUA" }, \
	{ XBF_FLUSH,		"FLUSH" }, \
	{ XBF_TRYLOCK,		"TRYLOCK" },	/* should never be set */\
	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
	{ _XBF_PAGES,		"PAGES" }, \
	{ _XBF_KMEM,		"KMEM" }, \
	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
	{ _XBF_COMPOUND,	"COMPOUND" }, \
	{ _XBF_LRU_DISPOSE,	"LRU_DISPOSE" }


/*
 * The dfs_buftarg contains 2 notions of "sector size" -
 *
 * 1) The metadata sector size, which is the minimum unit and
 *    alignment of IO which will be performed by metadata operations.
 * 2) The device logical sector size
 *
 * The first is specified at mkfs time, and is stored on-disk in the
 * superblock's sb_sectsize.
 *
 * The latter is derived from the underlying device, and controls direct IO
 * alignment constraints.
 */
typedef struct dfs_buftarg {
	dev_t			bt_dev;
	struct block_device	*bt_bdev;
	struct backing_dev_info	*bt_bdi;
	struct dfs_mount	*bt_mount;
	unsigned int		bt_meta_sectorsize;
	size_t			bt_meta_sectormask;
	size_t			bt_logical_sectorsize;
	size_t			bt_logical_sectormask;

	/* LRU control structures */
	struct shrinker		bt_shrinker;
	struct list_head	bt_lru;
	spinlock_t		bt_lru_lock;
	unsigned int		bt_lru_nr;
} dfs_buftarg_t;

struct dfs_buf;
typedef void (*dfs_buf_iodone_t)(struct dfs_buf *);


#define XB_PAGES	2

struct dfs_buf_map {
	dfs_daddr_t		bm_bn;	/* block number for I/O */
	int			bm_len;	/* size of I/O */
};

#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
	struct dfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };

struct dfs_buf_ops {
	void (*verify_read)(struct dfs_buf *);
	void (*verify_write)(struct dfs_buf *);
};

typedef struct dfs_buf {
	/*
	 * first cacheline holds all the fields needed for an uncontended cache
	 * hit to be fully processed. The semaphore straddles the cacheline
	 * boundary, but the counter and lock sits on the first cacheline,
	 * which is the only bit that is touched if we hit the semaphore
	 * fast-path on locking.
	 */
	struct rb_node		b_rbnode;	/* rbtree node */
	dfs_daddr_t		b_bn;		/* block number of buffer */
	int			b_length;	/* size of buffer in BBs */
	atomic_t		b_hold;		/* reference count */
	atomic_t		b_lru_ref;	/* lru reclaim ref count */
	dfs_buf_flags_t		b_flags;	/* status flags */
	struct semaphore	b_sema;		/* semaphore for lockables */

	/*
	 * concurrent access to b_lru and b_lru_flags are protected by
	 * bt_lru_lock and not by b_sema
	 */
	struct list_head	b_lru;		/* lru list */
	dfs_buf_flags_t		b_lru_flags;	/* internal lru status flags */
	wait_queue_head_t	b_waiters;	/* unpin waiters */
	struct list_head	b_list;
	struct dfs_perag	*b_pag;		/* contains rbtree root */
	dfs_buftarg_t		*b_target;	/* buffer target (device) */
	void			*b_addr;	/* virtual address of buffer */
	struct work_struct	b_iodone_work;
	dfs_buf_iodone_t	b_iodone;	/* I/O completion function */
	struct completion	b_iowait;	/* queue for I/O waiters */
	void			*b_fspriv;
	struct dfs_trans	*b_transp;
	struct page		**b_pages;	/* array of page pointers */
	struct page		*b_page_array[XB_PAGES]; /* inline pages */
	struct dfs_buf_map	*b_maps;	/* compound buffer map */
	struct dfs_buf_map	__b_map;	/* inline compound buffer map */
	int			b_map_count;
	int			b_io_length;	/* IO size in BBs */
	atomic_t		b_pin_count;	/* pin count */
	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
	unsigned int		b_page_count;	/* size of page array */
	unsigned int		b_offset;	/* page offset in first page */
	unsigned short		b_error;	/* error code on I/O */
	const struct dfs_buf_ops	*b_ops;

#ifdef DFS_BUF_LOCK_TRACKING
	int			b_last_holder;
#endif
} dfs_buf_t;

/* Finding and Reading Buffers */
struct dfs_buf *_dfs_buf_find(struct dfs_buftarg *target,
			      struct dfs_buf_map *map, int nmaps,
			      dfs_buf_flags_t flags, struct dfs_buf *new_bp);

static inline struct dfs_buf *
dfs_incore(
	struct dfs_buftarg	*target,
	dfs_daddr_t		blkno,
	size_t			numblks,
	dfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return _dfs_buf_find(target, &map, 1, flags, NULL);
}

struct dfs_buf *_dfs_buf_alloc(struct dfs_buftarg *target,
			       struct dfs_buf_map *map, int nmaps,
			       dfs_buf_flags_t flags);

static inline struct dfs_buf *
dfs_buf_alloc(
	struct dfs_buftarg	*target,
	dfs_daddr_t		blkno,
	size_t			numblks,
	dfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return _dfs_buf_alloc(target, &map, 1, flags);
}

struct dfs_buf *dfs_buf_get_map(struct dfs_buftarg *target,
			       struct dfs_buf_map *map, int nmaps,
			       dfs_buf_flags_t flags);
struct dfs_buf *dfs_buf_read_map(struct dfs_buftarg *target,
			       struct dfs_buf_map *map, int nmaps,
			       dfs_buf_flags_t flags,
			       const struct dfs_buf_ops *ops);
void dfs_buf_readahead_map(struct dfs_buftarg *target,
			       struct dfs_buf_map *map, int nmaps,
			       const struct dfs_buf_ops *ops);

static inline struct dfs_buf *
dfs_buf_get(
	struct dfs_buftarg	*target,
	dfs_daddr_t		blkno,
	size_t			numblks,
	dfs_buf_flags_t		flags)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return dfs_buf_get_map(target, &map, 1, flags);
}

static inline struct dfs_buf *
dfs_buf_read(
	struct dfs_buftarg	*target,
	dfs_daddr_t		blkno,
	size_t			numblks,
	dfs_buf_flags_t		flags,
	const struct dfs_buf_ops *ops)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return dfs_buf_read_map(target, &map, 1, flags, ops);
}

static inline void
dfs_buf_readahead(
	struct dfs_buftarg	*target,
	dfs_daddr_t		blkno,
	size_t			numblks,
	const struct dfs_buf_ops *ops)
{
	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
	return dfs_buf_readahead_map(target, &map, 1, ops);
}

struct dfs_buf *dfs_buf_get_empty(struct dfs_buftarg *target, size_t numblks);
void dfs_buf_set_empty(struct dfs_buf *bp, size_t numblks);
int dfs_buf_associate_memory(struct dfs_buf *bp, void *mem, size_t length);

struct dfs_buf *dfs_buf_get_uncached(struct dfs_buftarg *target, size_t numblks,
				int flags);
struct dfs_buf *dfs_buf_read_uncached(struct dfs_buftarg *target,
				dfs_daddr_t daddr, size_t numblks, int flags,
				const struct dfs_buf_ops *ops);
void dfs_buf_hold(struct dfs_buf *bp);

/* Releasing Buffers */
extern void dfs_buf_free(dfs_buf_t *);
extern void dfs_buf_rele(dfs_buf_t *);

/* Locking and Unlocking Buffers */
extern int dfs_buf_trylock(dfs_buf_t *);
extern void dfs_buf_lock(dfs_buf_t *);
extern void dfs_buf_unlock(dfs_buf_t *);
#define dfs_buf_islocked(bp) \
	((bp)->b_sema.count <= 0)

/* Buffer Read and Write Routines */
extern int dfs_bwrite(struct dfs_buf *bp);
extern void dfs_buf_ioend(dfs_buf_t *,	int);
extern void dfs_buf_ioerror(dfs_buf_t *, int);
extern void dfs_buf_ioerror_alert(struct dfs_buf *, const char *func);
extern void dfs_buf_iorequest(dfs_buf_t *);
extern int dfs_buf_iowait(dfs_buf_t *);
extern void dfs_buf_iomove(dfs_buf_t *, size_t, size_t, void *,
				dfs_buf_rw_t);
#define dfs_buf_zero(bp, off, len) \
	    dfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)

extern int dfs_bioerror_relse(struct dfs_buf *);

static inline int dfs_buf_geterror(dfs_buf_t *bp)
{
	return bp ? bp->b_error : ENOMEM;
}

/* Buffer Utility Routines */
extern dfs_caddr_t dfs_buf_offset(dfs_buf_t *, size_t);

/* Delayed Write Buffer Routines */
extern bool dfs_buf_delwri_queue(struct dfs_buf *, struct list_head *);
extern int dfs_buf_delwri_submit(struct list_head *);
extern int dfs_buf_delwri_submit_nowait(struct list_head *);

/* Buffer Daemon Setup Routines */
extern int dfs_buf_init(void);
extern void dfs_buf_terminate(void);

#define DFS_BUF_ZEROFLAGS(bp) \
	((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
			    XBF_SYNCIO|XBF_FUA|XBF_FLUSH| \
			    XBF_WRITE_FAIL))

void dfs_buf_stale(struct dfs_buf *bp);
#define DFS_BUF_UNSTALE(bp)	((bp)->b_flags &= ~XBF_STALE)
#define DFS_BUF_ISSTALE(bp)	((bp)->b_flags & XBF_STALE)

#define DFS_BUF_DONE(bp)	((bp)->b_flags |= XBF_DONE)
#define DFS_BUF_UNDONE(bp)	((bp)->b_flags &= ~XBF_DONE)
#define DFS_BUF_ISDONE(bp)	((bp)->b_flags & XBF_DONE)

#define DFS_BUF_ASYNC(bp)	((bp)->b_flags |= XBF_ASYNC)
#define DFS_BUF_UNASYNC(bp)	((bp)->b_flags &= ~XBF_ASYNC)
#define DFS_BUF_ISASYNC(bp)	((bp)->b_flags & XBF_ASYNC)

#define DFS_BUF_READ(bp)	((bp)->b_flags |= XBF_READ)
#define DFS_BUF_UNREAD(bp)	((bp)->b_flags &= ~XBF_READ)
#define DFS_BUF_ISREAD(bp)	((bp)->b_flags & XBF_READ)

#define DFS_BUF_WRITE(bp)	((bp)->b_flags |= XBF_WRITE)
#define DFS_BUF_UNWRITE(bp)	((bp)->b_flags &= ~XBF_WRITE)
#define DFS_BUF_ISWRITE(bp)	((bp)->b_flags & XBF_WRITE)

/*
 * These macros use the IO block map rather than b_bn. b_bn is now really
 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 * is safe to do.
 *
 * In future, uncached buffers will pass the block number directly to the io
 * request function and hence these macros will go away at that point.
 */
#define DFS_BUF_ADDR(bp)		((bp)->b_maps[0].bm_bn)
#define DFS_BUF_SET_ADDR(bp, bno)	((bp)->b_maps[0].bm_bn = (dfs_daddr_t)(bno))

static inline void dfs_buf_set_ref(struct dfs_buf *bp, int lru_ref)
{
	atomic_set(&bp->b_lru_ref, lru_ref);
}

static inline int dfs_buf_ispinned(struct dfs_buf *bp)
{
	return atomic_read(&bp->b_pin_count);
}

static inline void dfs_buf_relse(dfs_buf_t *bp)
{
	dfs_buf_unlock(bp);
	dfs_buf_rele(bp);
}

static inline int
dfs_buf_verify_cksum(struct dfs_buf *bp, unsigned long cksum_offset)
{
	return dfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
				cksum_offset);
}

static inline void
dfs_buf_update_cksum(struct dfs_buf *bp, unsigned long cksum_offset)
{
	dfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
			 cksum_offset);
}

/*
 *	Handling of buftargs.
 */
extern dfs_buftarg_t *dfs_alloc_buftarg(struct dfs_mount *,
			struct block_device *, int, const char *);
extern void dfs_free_buftarg(struct dfs_mount *, struct dfs_buftarg *);
extern void dfs_wait_buftarg(dfs_buftarg_t *);
extern int dfs_setsize_buftarg(dfs_buftarg_t *, unsigned int, unsigned int);

#define dfs_getsize_buftarg(buftarg)	block_size((buftarg)->bt_bdev)
#define dfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)

#endif	/* __DFS_BUF_H__ */
